<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <link rel="stylesheet" href="./css/index.css" />
    <title>记事本</title>
  </head>
  <body>
    <!-- 主体区域 -->
    <section id="app">
      <!-- 输入框 -->
      <header class="header">
        <h1>小黑记事本</h1>
        <input v-model="todoName" placeholder="请输入任务" class="new-todo" />
        <button @click="add" class="add">添加任务</button>
      </header>
      <!-- 列表区域 -->
      <section class="main">
        <ul class="todo-list">
          <li class="todo" v-for="(item,index) in list" :key="item.id">
            <div class="view">
              <span class="index">{{ index + 1 }}.</span>
              <label>{{ item.name }}</label>
              <button class="destroy" @click="del(item.id)"></button>
            </div>
          </li>
        </ul>
      </section>
      <!-- 统计和清空 -->
      <footer class="footer" v-show="list.length > 0">
        <!-- 统计 -->
        <span class="todo-count">
          合 计:<strong> {{ list.length }} </strong>
        </span>
        <!-- 清空 -->
        <button @click="list = []" class="clear-completed">清空任务</button>
      </footer>
    </section>

    <!-- 底部 -->
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
    <script>
      const app = new Vue({
        el: "#app",
        // 数据
        data: {
          // 输入框的值
          todoName: "",
          // 数组列表
          list: [
            { id: 1, name: "吃饭饭" },
            { id: 2, name: "睡觉觉" },
            { id: 3, name: "写代码" },
          ],
        },
        // 方法
        methods: {
          // （事件处理函数）
          del(id) {
            // 过滤掉当前 id 项（删除）
            this.list = this.list.filter((v) => v.id !== id);
          },
          add() {
            // 添加前，判断是否为空
            if (this.todoName.trim() === "") {
              return alert("请输入任务");
            }
            // 添加
            this.list.unshift({
              id: Date.now(),
              name: this.todoName,
            });
            // 添加后，清空输入框
            this.todoName = "";
          },
        },
      });
    </script>
  </body>
</html>
